1. Field of Invention
The invention relates to an ink jet head for performing a recording operation on a recording medium by jetting ink droplets from nozzles via energy generated by energy generating elements. Particularly, the invention relates to an ink jet head for performing a recording operation on a recording medium by jetting ink disposed in ink chambers from nozzles that communicate with the ink chambers by displacing piezoelectric elements through selectively applying drive voltages to the piezoelectric elements.
2. Description of Related Art
A conventional structure of an input unit for transmitting voltage applying signals for displacing piezoelectric elements to electrodes formed in ink chambers is disclosed in U.S. Pat. No. 5,598,196.
As shown in FIGS. 12 and 13, a cover plate 424 is provided on a piezoelectric body 412 to cover a plurality of ink channels formed in the piezoelectric body 412. Electrodes 422 are formed on side surfaces of the ink channels 416 and electrical conductors 426 are formed on a rear surface (a surface facing the ink channels) of the cover plate 424 at positions corresponding to the ink channels 416. Further, the electrical conductors 426 formed on the rear surface of the cover plate 424 and the electrodes 422 formed on the side surfaces of the ink channels 416 at positions corresponding to the electrical conductors 426, are connected to each other. As shown in FIG. 13, the cover plate 424 and the electrical conductors 426 formed on the rear surface of the cover plate 424, project from an end surface of the piezoelectric body 412 at an end surface opposite to the end where a nozzle plate 430 is provided. A pattern of electrical contact pads 438 is formed on the electrical conductors 426 at the end portions thereof.
However, according to the above-described structure, the electrical conductors 426 must be formed on the rear surface of the cover plate 424 before the cover plate 424 can be arranged on the piezoelectric body 412. However, when the cover plate 424 is arranged on the piezoelectric body 412, it is very difficult to accurately form the electrical conductors 426 on the cover plate 424 such that the electrical conductors 426 are brought into contact with the electrodes 422 provided on the side surfaces of the ink channels 416, which reduces manufacturing efficiency. Also, it is very difficult to accurately arrange the cover plate 424 on the piezoelectric body 412 such that the electrical conductors 426 formed on the rear surface of the cover plate 424 are brought into contact with the electrodes 422 provided on the side surfaces of the ink channels 416 corresponding to the electric conductors 426.
Further, according to the above-described structure, the electrical conductors 426 provided on the cover plate 424 face the ink channels 416 in an exposed state. Therefore, the electrical conductors 426 are always in contact with ink disposed in the ink channels 416. Therefore, the electrical conductors 426 are corroded by ink so that the voltage applying signals cannot be firmly transmitted to the electrodes 422 which are connected to the electrical conductors 426, which prevents the jetting of ink.